The best gleaning crews can bring that figure up to about 98 percent of the crop, close to hand-picking rates while costing 20 to 30 cents per box less, he says.
Abscission’s potential to reduce the amount of gleaning necessary could alter that equation.
Changes in tree and grove architecture as well as machine improvements could help raise recovery rates, Roka says.
“It’s all about capacity and improving the total boxes harvested per season,” he says. “Anything that increases capacity will drive down the unit cost.”
“If there are no major changes to the machines, growers or harvest contractors might be reluctant to invest in a harvester,” Burns says.
“We’ve stagnated on the efficiency of the machines,” Roka says. “There haven’t been improvements in seven or eight years.”
Also ripe for improvement is debris reduction. The force now needed to shake off fruit brings down leaves and branches in amounts that draw processor complaints. Applying an abscission agent could cut debris loads through reduced shaking force, he says.
Machinery trends in blueberries
Southern blueberry growers are seeing a flurry of new and improved harvesting machines, but fresh-market fruit prices and concerns about fruit quality mean many still stick with hand-picking.
Breeding programs focus on southern highbush varieties with firmer flesh that bruises less easily, says Gerard Krewer, small-fruit specialist at the University of Georgia in Tifton.
Under the right weather conditions, rabbiteye varieties hold up well to mechanical harvesting for the fresh market, but southern highbush varieties generally are too soft, Krewer says.
Also important in evaluating new releases are a concentrated ripening period to reduce the number of harvesting passes, strong root systems that hold up to harvesting machines, and fruit that detaches easily with limited ground loss, he says.
Pruning can correct a tendency toward low, spreading branches that hinder mechanical harvesters, but breeding a variety that grows more upright would limit pruning needs.